Posts and private carriers frequently provide discounts to mailers who presort mail. The discounts vary from country to country and are often dependent upon the level of presort. The more specifically the mail has been sorted in relation to delivery by the Post or carrier, the greater the discount.
These mail sortations implemented by the mailer, by the Posts or the private carriers often utilize a multiple-pass radix sort algorithm. The United States National Institute of Standards and Technology (USNIST) defines a radix sort as “a multiple pass distribution sort algorithm that distributes each item to a bucket according to part of the system's key, beginning with the least significant part of the key.” After each pass, items are collected from the buckets or bins, keeping the items in order, then re-distributed according to the next most significant part of the key. In a mailing system radix-type sortation, the key can be a delivery point sequence number accessed through a United States Postal Service (USPS) ZIP code, and the bucket can be the mailing system destination sortation bin. Use of a radix sort allows mail pieces to be sorted into delivery point sequence (carrier walk sequence), and eliminates the need for the delivery person to sort mail by hand before delivery. However, in implementing multiple pass sortations of this type, to achieve a delivery point sequence requires that the ordering of mail from prior sortation passes be maintained when the mail pieces from each of the sortation bins are combined for the next sortation pass.
Current systems for pre-sorting mail for presentation to a Post or a carrier typically do not make good use of available information to improve processing efficiency. Frequently, when mail is processed, the first sortation pass through mailing system sortation equipment is often a data gathering or rough sortation pass. Typically, this first pass through the sorter is employed to: read address information; gather address information for development of subsequent sortation schemes; apply USPS POSTNET delivery point bar codes and PLANET track and trace bar codes if they have not already been applied to the mail; and, build a postal code volume file that will be processed by pre-sort software to build the sortation scheme and compute postal work sharing discounts.
USPS POSTal Numeric Encoding Technique (POSTNET) bar codes are printed on the face of the envelope and are read by the bar code reading system. The POSTNET specifications are documented in the USPS Domestic Mail Manual issue 58 in section C840 (bar coding standards for letters and flats) and in USPS Publication 25 (Designing letter mail) in chapter 4. The POSTNET bar code encodes the destination ZIP code (postal code) on the face of the mail piece and is employed for the sortation process. The USPS has also developed the PostaL Alpha Numeric Encoding Technique (PLANET) bar code to enable tracing and tracking of mail pieces by providing a unique identifier for each mailing. In combination with the POSTNET bar code identifying the destination, PLANET bar codes make it possible to uniquely identify each mail piece. The encoding scheme is the complement of the POSTNET encoding scheme (three tall bars and two short bars in each cluster of five). Thus, the same bar code reader can operate to read both POSTNET and PLANET bar codes. At the same time, the different symbology conventions make it possible to distinguish the two bar codes (mostly tall vs. mostly short bars). Posts throughout the world have developed arrangements for various other types of delivery coding and track and trace systems for processing and tracking and tracing mail.
This first pass sortation is not optimized. This is frequently because of the lack of address information for development of subsequent sortation schemes. The lack of information about the mail pieces prevents the sorter from running a sortation scheme optimized to the particular set of mail pieces to be processed. The sorter process may require one or more sortation passes than would have been required if the address information were available for analysis and processing prior to the first mail piece pass. As a result, the cost to process the mail is increased because, for example, the time to unload the mail from sortation bins of a sorter for each sortation pass or run can be substantial, particularly when large sorters are swept (emptied) of mail in the bins. Also the machine utilization may require additional operators and even additional sortation equipment to process a given volume of mail pieces within a specified time period.
The above problems are often compounded with windowed envelopes. Window envelopes are often used to simplify addressing of mail by allowing the address printed on the mail piece contents to be visible externally. This eliminates the risk of mismatching external printed addresses with the internal contents. Unfortunately, mail pieces are often smaller than the envelope and with automated processing; the inserted addressed pieces may shift and obscure portions of the address or preprinted bar codes. Such mail is not possible to process reliably on automation equipment and is not acceptable to the USPS.
Extra passes of the mail through the sortation system not only expose the mail to possible damage, but also represent a significant time and labor effort. Preparing and staging the mail for each such sortation pass consumes additional time and labor, and machine processing time. Furthermore, the additional sortation and staging further expose the mail to possible errors if it is staged incorrectly and will further extend the mail processing time.
Various prior designs of bar code sorters (BCS) and multiple line optical character readers (MLOCR) have recorded bar code information and text information from mail pieces passing the BCR or MLOCR stations for generally three main purposes. First, it has been used to allow analysis of the timing of pieces passing the readers during system tests. Secondly, POSTNET bar code data is captured on production systems to gather the list of mail pieces that have passed through the system. This data is then processed through pre-sort discount sort software to compute the postal discounts that will be obtained and to allow creation and optimization of multiple pass sortation plans that will properly sequence the mail to achieve the pre-sort discounts. Third, POSTNET and PLANET code data is captured by the USPS on their sorting equipment and relayed to mailers or recipients to enable them to see the progress of the mail pieces through the postal transportation system (tracing and tracking information). These prior instances of data capture from mail pieces on sorting equipment are very limited in their use and any unsuccessful read or reconstruction of the address data will preclude POSTNET barcoding of the mail pieces. It will result in rejection of the mail piece and the need to reprocess that piece. If the mail pieces (such as billing statements) were printed and therefore organized in any sequence initially (e.g. address order), that organization would be disrupted when pieces are rejected and lost from the mail stream.
Prior mail preparation systems have utilized mail-run data files (MRDF) which describe the intended contents of each envelope and may be used on a mail insertion, sealing, and postage payment system to ensure that the correct items are contained in each envelope (e.g. a two page statement, a privacy notice, and a credit card offer). In the past, data from the MRDF used for preparation of a mailing has also been passed to the pre-sort software to prepare the mailing manifests, the sortation plans, and calculate the work sharing discounts. Existing mail creation and sortation processes may create mail manifests or informational reports in standardized computer file formats, such as “mail.dat”, for reporting the characteristics of mailings to the USPS. However, these systems have not effectively employed the data accessed during the first pass.
“Quick kill sortation plans” assign dedicated bins to mail that is known to have the critical mass to be packaged, for example, for the USPS or other Posts, directly from that sortation bin without the need to run that mail again. However, these quick kill sortation plans are based on having previously obtained information about the type of mail that will be processed by the sorter before the sortation process begins.